Multi-layered electrode for ultracapacitors

Abstract

A multi-layer electrode includes a current collector having opposing first and second major surfaces, a fused carbon layer formed over one or both of the major surfaces, a conductive adhesion layer formed over each fused carbon layer, and an activated carbon layer formed over each conductive adhesive layer. The multi-layer electrode can be incorporated into a high energy density, high power density device such as an electric double layer capacitor.

What is claimed is: 
     
       1. A multilayer electrode for an electric double layer capacitor, comprising:
 a current collector having opposing major surfaces; 
 a continuous layer of fused carbon formed over substantially all of one or both of the major surfaces; 
 a continuous conductive adhesion layer comprising carbon black, graphite and a binder formed over each fused carbon layer; and 
 an activated carbon layer formed over each conductive adhesion layer. 
 
     
     
       2. The multilayer electrode according to  claim 1 , wherein the fused carbon layer is formed over both of the major surfaces of the current collector. 
     
     
       3. The multilayer electrode according to  claim 2 , having a thru-plane area-specific resistance of less than 0.1 ohm-cm 2 . 
     
     
       4. The multilayer electrode according to  claim 1 , wherein the fused carbon layer has an average thickness of about 0.1 to 2 micrometers and the conductive adhesion layer has an average thickness of about 0.25 to 5 micrometers. 
     
     
       5. The multilayer electrode according to  claim 1 , wherein the conductive adhesion layer comprises about 40-60 wt. % of carbon black particles having an average particle size of between about 0.1 and 1 micrometers, and about 40-60 wt. % of graphite particles having an average particle size of between about 5 and 50 micrometers. 
     
     
       6. The multilayer electrode according to  claim 1 , wherein the activated carbon layer comprises microporous activated carbon. 
     
     
       7. The multilayer electrode according to  claim 1 , wherein the activated carbon layer comprises activated carbon, carbon black and a binder. 
     
     
       8. The multilayer electrode according to  claim 1 , wherein the activated carbon layer comprises 80-90 wt. % activated carbon, 0-10 wt. % carbon black and about 5-15 wt. % PTFE. 
     
     
       9. The multilayer electrode according to  claim 1 , wherein activated carbon in the activated carbon layer comprises:
 pores having a size of ≦1 nm, which provide a combined pore volume of ≧0.3 cm 3 /g; 
 pores having a size of from >1 nm to ≦2 nm, which provide a combined pore volume of ≧0.05 cm 3 /g; and 
 <0.15 cm 3 /g combined pore volume of any pores having a size of >2 nm. 
 
     
     
       10. The multilayer electrode according to  claim 1 , wherein an interaction zone between the current collector and the activated carbon layer ranges from about 0.1 to 1 microns. 
     
     
       11. An electric double layer capacitor comprising the multilayer electrode according to  claim 1 . 
     
     
       12. A device comprising the electric double layer capacitor according to  claim 11 . 
     
     
       13. A method of forming a multilayer electrode for an electric double layer capacitor, said method comprising the acts of:
 providing a current collector having opposing major surfaces; 
 forming a continuous layer of fused carbon over substantially all of one or both of the major surfaces; 
 forming a continuous conductive adhesion layer over each fused carbon layer to form a pre-electrode assembly; and 
 forming an activated carbon layer over each conductive adhesion layer. 
 
     
     
       14. The method according to  claim 13 , wherein forming the conductive adhesion layer comprises a method selected from the group consisting of dip-coating, gravure coating, tape casting, curtain coating, slot die coating, meniscus coating and spray coating. 
     
     
       15. The method according to  claim 13 , further comprising heating the pre-electrode assembly at a temperature effective to remove adsorbed water and/or residual organics prior to forming the activated carbon layer. 
     
     
       16. The method according to  claim 13 , wherein the activated carbon layer is laminated over each conductive adhesion layer.